internet services some samples: email, login, file transfer, news document distribution, web...
TRANSCRIPT
Internet Services
Some samples: email, login, file transfer, news document distribution, web services, etc…
TCP Port: 25
uses Simple Mail Transfer Protocol
Clients:
mailx, pegasus, MS-outlook, Netscape messenger
Servers:
Sendmail (Unix), MS-Exchange (NT),
Netscape Messaging Server (Unix, NT)
Terminal Emulation
Port: 23 (uses Telnet Protocol)
Clients: telnet
Servers: telnetd
Port: 22
Clients: ssh
Servers: sshd
File Transfer
Uses File Transfer Protocol
Port: 21
Clients: ftp
Servers: ftpd (Unix), IIS (NT and Windows)
News
Uses Network News Transfer Protocol
Port: 119
Clients: MS-Outlook, Netscape Collabra
Servers: nntpd(Unix)
Electronic Documents
Gopher Protocol
Port: 70
Clients: wingopher
Servers: IIS
Web Services
Uses HTML Protocols
port: 80
Clients: Netscape Navigator, MS IE
Servers: IIS for Windows Platform, Apache Tomcat for Java Platform
With each of the preceding,
multiple clients may communicate with
a single server
The normal usage of this application is to create a message for another user on a local or remote computer system and have it delivered electronically.
An example of “push” delivery
e.g. mail [email protected]: How is the Project?Message-----------------------------------------------Hi, I got your last message.........etc
The message is sent from the originating mail serving application to the destination mail serving application via a route that may pass through many mail servers on its way.
Mail servers
Mail clients
Received: from Received: from (2)(2) ALPHA8.MONASH.EDU.AUALPHA8.MONASH.EDU.AU by by (1)(1) silas.monash.edu.au silas.monash.edu.au (8.9.3/1.1.29.3/16Feb01-1022AM) id XAA0000955685; Tue, 23 Apr 2002 23:50:56 (8.9.3/1.1.29.3/16Feb01-1022AM) id XAA0000955685; Tue, 23 Apr 2002 23:50:56 +1000 (EST)+1000 (EST)
Received: from Received: from blammo.monash.edu.aublammo.monash.edu.au ([129.179.1.74]) by ([129.179.1.74]) by (3)(3) vaxh.monash.edu.auvaxh.monash.edu.au (PMDF V5.2-31 #39306) with ESMTP id (PMDF V5.2-31 #39306) with ESMTP id <[email protected]> for <[email protected]> for [email protected]; Tue, 23 Apr 2002 23:50:48 [email protected]; Tue, 23 Apr 2002 23:50:48 +1000
Received: from blammo (unknown [127.0.0.1]) by Received: from blammo (unknown [127.0.0.1]) by (4)(4) localhost (Postfix) with localhost (Postfix) with ESMTP id 5425712C002 for <[email protected]>; Tue, 23 Apr ESMTP id 5425712C002 for <[email protected]>; Tue, 23 Apr 2002 13:50:43 +0000 (/etc/localtime)2002 13:50:43 +0000 (/etc/localtime)
Received: from Received: from mail1.monash.edu.aumail1.monash.edu.au (bigted.monash.edu.au [129.179.11.60]) by (bigted.monash.edu.au [129.179.11.60]) by (5)(5) blammo.monash.edu.au (Postfix) with ESMTP id 14A8512C002 for blammo.monash.edu.au (Postfix) with ESMTP id 14A8512C002 for <[email protected]>; Tue, 23 Apr 2002 23:50:43 +1000 (EST)<[email protected]>; Tue, 23 Apr 2002 23:50:43 +1000 (EST)
Received: from Received: from ALPHA1.MONASH.EDU.AUALPHA1.MONASH.EDU.AU ([129.179.1.1]) by ([129.179.1.1]) by (6)(6) mail1.monash.edu.au (Netscape Messaging Server 4.15) with ESMTP id mail1.monash.edu.au (Netscape Messaging Server 4.15) with ESMTP id GV0X4I00.NBA for <[email protected]>; Tue, 23 Apr 2002 23:50:42 GV0X4I00.NBA for <[email protected]>; Tue, 23 Apr 2002 23:50:42 +1000+1000
SMTP Headers
Received: from Received: from (8)(8) blammo.monash.edu.au blammo.monash.edu.au ([129.179.1.74]) by ([129.179.1.74]) by (7)(7) vaxc.monash.edu.au vaxc.monash.edu.au (PMDF V6.1 #39306) with ESMTP id (PMDF V6.1 #39306) with ESMTP id <[email protected]> for <[email protected]> for [email protected] (ORCPT [email protected]); [email protected] (ORCPT [email protected]); Tue, 23 Apr 2002 23:50:31 +1000Tue, 23 Apr 2002 23:50:31 +1000
Received: from blammo (unknown [127.0.0.1]) by localhost (Postfix) with ESMTP id Received: from blammo (unknown [127.0.0.1]) by localhost (Postfix) with ESMTP id 762F512C002 for <[email protected]>; Tue, 23 Apr 2002 762F512C002 for <[email protected]>; Tue, 23 Apr 2002 13:50:30 +0000 (/etc/localtime)13:50:30 +0000 (/etc/localtime)
Received: from Received: from (9)(9) mail021.syd.optusnet.com.au mail021.syd.optusnet.com.au (mail021.syd.optusnet.com.au (mail021.syd.optusnet.com.au [200.39.20.161]) by blammo.monash.edu.au (Postfix) with ESMTP id 1F4AE12C002 [200.39.20.161]) by blammo.monash.edu.au (Postfix) with ESMTP id 1F4AE12C002 for <[email protected]>; Tue, 23 Apr 2002 23:50:30 +1000 (EST)for <[email protected]>; Tue, 23 Apr 2002 23:50:30 +1000 (EST)
Received: from CO3025549A Received: from CO3025549A (10)(10) ( (c16494.frank1.vic.optusnet.com.au c16494.frank1.vic.optusnet.com.au [200.39.205.113])[200.39.205.113])
SMTP Headers
by mail021.syd.optusnet.com.au (8.11.1/8.11.1) with SMTP id g3NDoRi15920 for by mail021.syd.optusnet.com.au (8.11.1/8.11.1) with SMTP id g3NDoRi15920 for <[email protected]>; Tue, 23 Apr 2002 23:50:27 +1000 Date: Tue, <[email protected]>; Tue, 23 Apr 2002 23:50:27 +1000 Date: Tue, 23 Apr 2002 23:51:34 +100023 Apr 2002 23:51:34 +1000From: Patrik <[email protected]>From: Patrik <[email protected]>Subject: QuestionsSubject: QuestionsTo: To: [email protected]@infotech.monash.edu.auMessage-id: <[email protected]>Message-id: <[email protected]>MIME-version: 1.0MIME-version: 1.0X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)Content-type: MULTIPART/MIXED; Content-type: MULTIPART/MIXED; BOUNDARY="Boundary_(ID_DI+xGCWXZlChun9D5NMJlw)"BOUNDARY="Boundary_(ID_DI+xGCWXZlChun9D5NMJlw)"Importance: NormalImportance: NormalX-Priority: 3 (Normal)X-Priority: 3 (Normal)X-MSMail-priority: NormalX-MSMail-priority: NormalParts/Attachments:Parts/Attachments:
SMTP Headers
SMTP Model
User Agent Local MTA
Processing Queue Processing Queue
MTA Relay Local MTA
Mailboxes
User Agent
The SMTP Model
MTA: A mail transfer agent exchanges mail over a TCP/IP connection
System administrator is responsible for setting up the MTA
SMTP defines a MTA that implements a system based upon the spooling of messages.
SMTP
First proposed in RFC821 Later updated in RFC822 – replaced X.400 Commands
HELO client identifies itselfMAIL/RCPT identifies originator and recipientDATA for sending the contents of the mailQUIT terminates the mail exchangeRSET aborts a transfer and resets both the endsVRFY to verify the address without actually sendingNOOP forces server to respond with OKEXPN expands a mailing listTURN lets client and server switch roles
Mailing Lists
To send mail to a group of users, mailing lists are often used.
A mail server is needed to distribute the mail messages to members of a mailing list.
List can be manually created, or may be automatically maintained.
Mailing Lists
Listservers maintaining automated lists receive mail messages from new list members requesting that they be added to the list.eg. subscribe cse3153Mailing Lists
List members can also remove themselves from the list.eg. unsubscribe cse3153Messages will be sent to all members of the list when
e-mail is sent to the listname email address on the computer that is hosting the list. eg. [email protected]
Terminal Connectivity
Allows remote users to log into computers that are attached to the network.
Users can be located anywhere that there is a network connection.
As if they were sitting at a terminal that was physically attached to that computer.
Moving files from one computerTo another over the Internet
FTPAssign1.doc Assign1.doc
COMPUTER AFTP Server
COMPUTER BFTP Client
Moving files from one computerTo another over the Internet
File Transfer
Anonymous ftp
To use ftp, a user normally must identify themselves with a username and password.
Having accounts for all possible users is impractical.
An anonymous user account is maintained on many ftp servers.
Anonymous ftp
The anonymous account is restricted to certain areas of the server and will normally have restricted privileges (e.g. may only be permitted to read and not write).
Most systems require the user's e-mail address to be typed instead of a password.
Anonymous ftp
Many ftp servers use the account ftp (its easier to type).
Most WWW browsers support ftp as a built in function making it easy to use file transfer
News
A network of news servers around the Internet implements the Network News Transfer Protocol (NNTP). These systems support a special-interest group type of information service.
News
Messages can be posted to a news group and will then be broadcast to all news servers over a period of time.
News
News messages can be read by anyone using a news client that is attached to a news server.
Most WWW browsers have NNTP plug-in applications
HTML
Hyper Text Markup Languagea simple markup language used to
create hypertext documents that are portable from one platform to another
HTML
HTML documents are SGML documents
ISO Standard 8879:1986 Information Processing Text and Office Systems; Standard Generalized Markup Language (SGML)
HTML
HTML describes the structure and organization of a document
It only suggests appropriate presentations of the document when processed
Tags define the start and end of headings, paragraphs, lists, character highlighting and links
URL - Uniform Resource Locator
A link or pointer to an object or resourceCould be a file, a HTML document on a
remote system etc
HTML
HTML was developed as part of the World Wide Web - a concept that was initiated at the CERN Laboratories(European Particle Physics Laboratories)
Web sites have home pagesthe first point of access
These point to other pages via URLshypertext pointing to address of the next
page
Browsers
Applications that connect to WWW servers
Send requests to the servers and receive responses in the form of web pages.
NCSA Mosaic, Lynx, Internet Explorer, Netscape Navigator.
HTTPD AdministrationRef: http://hoohoo.ncsa.uiuc.edu/docs/tutorials/
Virtual directory structure
Directory Indexing Security
Access control and user authentication
Secure serverchroot serverKereberos,
MD5 authentications Image maps
CGI Configurations Virtual Hosting Logfile rotations Starting, stopping, and
restarting the daemon Multiple DirectoryIndex KeepAlive Redirect Directives Server-side includes